This invention relates to plastic films and tubes such as plastic drip irrigation hose and other plastic products which are used with water. Different forms of drip irrigation devices are shown in the Delmer U.S. Pat. No. 4,548,360 and in the references of record in that patent.
One of the problems encountered in articles of this type is clogging of relatively small flow passages resulting from the growth of biological products such as algae and bacterial slimes.
It is known that copper sulfate in solution is a biocide, combatting bacterial slimes and algaes. Also, other materials such as chlorine, sulfuric acid and hydrochloric acid have been introduced into water systems for control of biological growth. These practices have problems, including the necessity of continuous introduction of the biocide in small amounts and the adverse effect of the introduced materials on the plastic product.
Another approach to the problem is set out in the Boyle et al U.S. Pat. No. 3,467,142, . This patent discloses a flow distributor for connection to a source of water and having an elongated body of plastic with a main flow passage and a plurality of smaller flow passages with a copper wire positioned within one or more of the flow passages.
There are problems with this proposed type of construction. The physical presence of the copper wire in some of the flow passages is an impediment to water flow. Manufacturing the hose or other product with the copper wire therein is difficult and uncertain. In sugar cane fields the irrigation hose or tape is retrieved every three to five years, and in some fields hose is replaced every year. Retrieving and disposing of the copper wire in the hose would be near impossible. If the wire is left in the field, it would be dangerous and would become tangled in the farm machinery.
Accordingly, it is an object of the present invention to provide a new and improved plastic film with biocide incorporated and apparatus and method for making such product.
It is a particular object of the invention to provide a new and improved plastic drip irrigation hose with primary and secondary passages and incorporating a biocide.
Other objects, advantages, features and results will more fully appear in the course of the following description.